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Joined: Jul 2003
Posts: 521
Oil Can Mechanic
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OP
Oil Can Mechanic
Joined: Jul 2003
Posts: 521 |
My spark plugs are getting sooty and misfiring after only a few hundred miles (3000 mi on 235 engine); are my plugs the wrong temperature or carb problem? I tried lowering the float valve, didn't change anything. Engine runs strong otherwise.
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Joined: Jan 2002
Posts: 30,701 Likes: 141
ChatMaster - 25,000
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ChatMaster - 25,000
Joined: Jan 2002
Posts: 30,701 Likes: 141 |
What spark plug are you running?
The "happy medium" for most driving conditions would be an AC45.
What kind of driving was done. A lot of cold starts and short trips would require a hotter plug.
Is the choke over choking when cold?
Is the vacuum power piston in the carburetor stuck in the full rich (power) position. This will make it run fairly well but is way too rich.
Posible cause valve stuck or incorrect insulator block under carburetor or a gasket on top of the block cutting off the vacuum port.
Gene Schneider
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Joined: Jul 2003
Posts: 521
Oil Can Mechanic
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OP
Oil Can Mechanic
Joined: Jul 2003
Posts: 521 |
Thanks CN. I installed the AC45s, we'll see if that helps. I mostly drive around town and the truck never really gets hot (I was using Autolite 303 plugs).
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Joined: Aug 2012
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ChatMaster - 1,000
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ChatMaster - 1,000
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What is the correct insulator?
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Joined: Jan 2002
Posts: 30,701 Likes: 141
ChatMaster - 25,000
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ChatMaster - 25,000
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Posts: 30,701 Likes: 141 |
What do you mean by insulator? The porclain body of the spark plug. They were smooth until 1956.
Gene Schneider
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Joined: Aug 2012
Posts: 1,381
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ChatMaster - 1,000
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You mention above "insulator block" under the carb. I am thinking you are referring to the spacer between the carb base and the intake mani. Sorry to confuse.
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Joined: Feb 2002
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ChatMaster - 1,000
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Heat riser free? Choke properly adjusted and working? No matter what short runs will result in some carbon fluff on the plugs as the mixture is rich and the engine is cold. 
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